JPS6278907A - Surface acoustic wave element - Google Patents

Abstract

PURPOSE:To improve manufacture yield and to obtain characteristics such as acoustic reflection and the suppression of the 2nd higher harmonic by connecting adjacent electrode fingers of nonintersection parts of comb-shaped electrodes of a surface acoustic wave element. CONSTITUTION:This surface acoustic wave element consists of two opposite comb-shaped electrodes 1, which each consists of plural electrode fingers 2. The electrode fingers of the comb-shaped electrodes cross each other partially to form an intersection part 3 and nonintersection part 4. The width and intervals 2 of the electrode fingers 2 are one-eight as large as the wavelength lambdaof a surface acoustic wave. The electrodes formed as mentioned above have plural power supply paths to the electrode fingers at the intersection part which is effective in operation at the noninsertion parts and the probability of a break of power supply due to the breaking of an electrode finger at a noninsertion part decreases greatly. Further, the area ratio of the electrode fingers and gaps between the electrode fingers is nearly constant on the whole, so characteristics are not caused by deterioration in acoustic wave to deteriorate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surface acoustic wave device, and prevents a decrease in yield due to electrode breakage by improving the shape of an electrode formed on a substrate. The purpose is to

[Conventional technology]

FIG. 3 shows an example of a commonly made surface acoustic wave excitation electrode in a surface acoustic wave device.

This surface acoustic wave excitation electrode is provided on a surface acoustic wave propagation substrate and is composed of two comb-shaped electrodes (1) facing each other. The comb-shaped electrode is composed of a plurality of electrode fingers (2), and the electrode fingers of the comb-shaped electrodes partially intersect with each other, forming an intersecting part (3) and a non-intersecting part (4). The inside of the electrode finger and the electrode finger spacing (61 are each formed to be 178 of the wavelength (λ) of the surface acoustic wave, and the surface acoustic wave of the desired wavelength (λ) is excited, but its @2 height is The tile wave is not excited.

Further, when surface acoustic waves are reflected from surfaces A and B, as shown by the arrows in FIG. 1, a phase difference of 1/2 λ is generated, and acoustic reflection is also suppressed.

However, in such a double electrode, since the width of the electrode finger (2) is as narrow as 1/8λ, there is a drawback that during manufacturing, disconnection due to electrode breakage easily occurs, lowering the yield.

A comb-shaped electrode disclosed in Japanese Patent Publication No. 59-52569 is cited as a conventional example of countermeasures against this drawback.

FIG. 4 shows the comb-shaped electrode disclosed in the above publication. As in Fig. 3, it is composed of two opposing comb-shaped electrodes +I+, forming mutual comb-shaped electrodes [the polar fingers (2) partially intersect, and the intersecting parts (3) and non-intersecting It forms part (4). The electrode finger part and the N-pole finger spacing (51) at the intersection are each formed to be 1/8λ, while the electrode at the non-intersection extends the two electrodes connected to the double electrode at the intersection. Connect them like this and extend them laterally to form an electrode finger ($1) with a width of 578λ.Furthermore,
An electrode finger with a width of 3Aλ is provided between the electrode fingers (6) with a width of 578λ. In this way, in the example of FIG. 4, the acoustic lengths Q+ and I! While maintaining good characteristics of suppressing the generation of second harmonics, the yield is improved by making the part of the electrode that is an effective electrode thick to 5/8λ during operation to prevent wire breakage.

[Problem that the invention seeks to solve]

However, in the example shown in FIG. 4, the ratio of the area occupied by the tS finger to the area occupied by the gap between the electrode fingers is different between the intersection and non-intersection, so the sound velocity of the surface acoustic wave at the electrode finger and the gap Since the speed of sound at is different,
The sound speeds at the intersection (31) and the non-intersection (4) are different.Therefore, there is a problem in that the surface acoustic waves do not propagate in parallel phase planes, resulting in deterioration of characteristics.

The present invention has been made to solve the above problems, and it maintains a uniform sound velocity, prevents deterioration of characteristics, suppresses acoustic reflection, suppresses the generation of second harmonics, and narrows the electrode finger portion. It is an object of the present invention to obtain a surface acoustic wave element equipped with a comb-like electrode, which can simultaneously suppress the decrease in yield associated with K.

[Means for solving problems]

The surface acoustic wave element according to the present invention has a comb-shaped 1! It is dangerous to provide a surface acoustic wave excitation electrode on a substrate in which adjacent aS fingers at non-intersecting portions of the electrodes are connected at some or more locations.

[Effect]

According to the present invention, by partially connecting adjacent electrode fingers of non-intersecting parts, 1! of the intersecting parts! By providing multiple paths for supplying power to the pole fingers, we are able to prevent the power supply from being cut off due to disconnection of some electrodes, thereby improving yield. ! The double electrode property of suppressing second harmonics is maintained.

[Embodiments of the invention]

FIG. 1 shows an embodiment according to the present invention. @Figure 3 and @4
Similar to the example in the figure, K, two opposing comb-tooth electric currents P1iill
The comb-shaped electrode consists of a plurality of electrode fingers (21). The electrode fingers of each comb-shaped electrode partially intersect, forming an intersecting part (3) and a non-intersecting part (4). The electrode finger (
The width of 21 and the electrode finger spacing (51fi) are each 1/8 of the wavelength (λ) of the surface acoustic wave. Electrode fingers at non-intersecting parts are connected to adjacent electrode fingers by bridges (7). ing.

In the electrodes formed in this way, there are multiple power supply paths to the electrode fingers at the intersection that are effective during f#h operation at the non-intersection, and the probability of power supply interruption due to disconnection of the electrode fingers at the non-intersection is low. is significantly reduced, and therefore the yield during manufacturing can be improved. Furthermore, since the ratio of the area occupied by the electrode fingers to the area occupied by the gaps between the tti fingers is substantially constant throughout, there is no deterioration of characteristics due to non-uniformity of sound speed. Furthermore, it maintains the good characteristics of acoustic reflection and suppression of @2 harmonic generation, which are characteristics of double electrodes.

In addition, since the above-mentioned actual example is a double electrode, the present invention can also be applied to a single electrode in which the ζ electrode finger portion and the electrode finger interval are 1/4λ. One embodiment is shown in FIG. In this figure, the distance between the electrode fingers and the 'rILM fingers is 1/4λ. This practical example is similar to the double electrode example, and has the effect of improving yield and preventing deterioration of characteristics due to non-uniformity of sound velocity.

In the above, the electrode finger portions are 1/8λ and 1/4λ. However, in accordance with the gist of the present invention, the adjacent N of the non-intersecting portions of the intersecting comb-like electrodes are A modified structure is obtained, but in either case, the same effects as in the above embodiment are achieved.

〔Effect of the invention〕

As described above, according to the present invention, by connecting adjacent electrode fingers of non-intersecting parts of the comb-shaped am in a surface acoustic wave element, it is possible to avoid deterioration of characteristics due to non-uniformity of sound speed. Accordingly, it is possible to obtain a surface acoustic wave element that improves manufacturing yield and maintains characteristics of acoustic reflection and suppression of second harmonics.

[Brief explanation of drawings]

@ Figure 1 is a plan view showing a comb-shaped electrode according to one embodiment of the present invention, Figure 2 is a plan view showing a comb-shaped electrode according to another embodiment of the present invention, and Figures 3 and 4 are conventional ones. FIG. 3 is a plan view showing a comb-shaped electrode. +11 is a comb-shaped electrode, (2) is an electrode finger, (31 is an intersecting part, +41 is a non-intersecting part, (51 is an electrode finger interval, (6) is a 5
/8λ width electrode fingers, (7) is a bridge. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] It consists of a substrate that serves as a propagation medium for surface acoustic waves, and a surface acoustic wave excitation electrode formed by a pair of comb-shaped electrodes made up of a plurality of electrode fingers provided on the surface of this substrate. In a surface acoustic wave element equipped with the surface acoustic wave excitation electrode, the electrode fingers of the comb-like electrodes partially intersect with each other to form intersecting parts and non-intersecting parts of the electrode fingers. , a surface acoustic wave device characterized in that a plurality of adjacent electrode fingers at non-intersecting portions are connected to each other at some or a plurality of locations.